Leaders of the BRICS emerging economies, which account for about a quarter of the world's wealth, meet in Johannesburg this week looking to widen the bloc's influence and push for a shift in global geopolitics.

South Africa's Cyril Ramaphosa is expected to host China's President Xi Jinping, India's Prime Minister Narendra Modi and Brazil's President Luiz Inacio Lula da Silva for the annual three-day summit starting on Tuesday.

Russian President Vladimir Putin also will join remotely.

Putin decided against attending in person as he is the target of an International Criminal Court arrest warrant that South Africa is in theory bound to enforce if he sets foot in the country.

Russian Foreign Minister Sergey Lavrov will travel to Johannesburg instead.

Representing billions of people across three continents, with economies undergoing varying levels of growth, the BRICS share one thing in common -- disdain for a world order they see as serving the interests of rich Western powers.

"The traditional global governing system has become dysfunctional, deficient and missing in action," Chen Xiaodong, the Chinese ambassador to Pretoria said at a briefing on Friday, adding the BRICS are "increasingly becoming a staunch force in defending international justice".

There is growing interest in the bloc -- at least 40 countries have expressed interest in joining, and 23 of those have formally submitted applications to become BRICS members.

- 'Polarised world' -

Anil Sooklal, South Africa's ambassador-at-large for Asia and the BRICS, told AFP on Friday that one of the reasons countries are lining up to join is "the very polarised world we live in, that has been further polarised by the Russia-Ukraine crisis, and where countries are being forced to take sides".

"Countries in the South don't want to be told who to support, how to behave and how to conduct their sovereign affairs. They are strong enough now to assert their respective positions," added Sooklal.

The BRICS have raised hope for countries looking to restructure the global "architecture", he said.

"The major markets are now in the Global South... but we are still on the margins in terms of global decision-making."

Lebogang Legodi, international politics lecturer at the University of Limpopo, agrees that many states keen on joining the group "are seeing BRICS as an alternative to the current hegemony" in world affairs.

Around 50 other leaders will attend a "friends of BRICS" programme during the summit, which will be held at a convention centre in the heart of Johannesburg's Sandton, historically referred to as the richest square-mile on the continent.

This year's gathering is themed "BRICS and Africa: Partnership for mutually accelerated growth, sustainable development and inclusive multilateralism".

It comes at "a critical inflection point," said Steven Gruzd of the Africa-Russia Africa project at the South African Institute of International Affairs.

"The current multilateral system is under strain," he said.

A decision on expanding the BRICS membership is expected at the end of the summit, according to Sooklal.

An upbeat Ramaphosa told a meeting of the ruling ANC party in Johannesburg on Saturday that "we are going to have a fantastic BRICS summit".

He said the presence of so many heads of state "goes to show the influence and the impact that South Africa" has in the world.

But experts closely watching the BRICS aren't very optimistic about the meeting's outcomes.

"I don't think this summit will yield those dramatic results because the power is still with Western countries. China is rising, but is not the dominant power yet," said SAIIA's Gruzd.

Formally launched in 2009, the BRICS now account for 23 percent of global GDP and 42 percent of the world's population.

The combined bloc represents more than 16 percent of the world's trade.